1. Black Holes and Extra Dimensions Jonathan Feng UC Irvine UCSD Particle Seminar 28 January 2003

2. January 2003UCSDFeng 2 The Standard Model Many interesting problems, but one obvious one: where’s gravity? Gravity is weak, becomes strong at M D ~ 10 18 GeV, far beyond experiment Suppose SM confined to D = 4, but gravity propagates in n extra dimensions of size L: For r  L, F gravity ~ 1/r 2 For r  L, F gravity ~ 1/r 2+n

3. January 2003UCSDFeng 3 … gravity EM Strength r M D -1 Gravity in Extra Dimensions

4. January 2003UCSDFeng 4 Strong Gravity at the Electroweak Scale If D > 4, M D < 10 18 GeV possible Suppose M D is 1 TeV, the electroweak unification scale The number of extra dims n then fixes L n=1 excluded by solar system, but n=2, 3,… are allowed by tests of Newtonian gravity Arkani-Hamed, Dimopoulos, Dvali (1998)

5. January 2003UCSDFeng 5 Tests of Newtonian Gravity Strength of Deviation Relative to Newtonain Gravity Long, Chan, Price; Hoyle et al.

6. January 2003UCSDFeng 6 Kaluza-Klein States Extra dimensions of size L  towers of Kaluza-Klein particles with masses ~ L -1 Large extra dims  light states KK states may appear at colliders, in astrophysics (supernova cooling, etc.), … f f f ’ graviton __

7. January 2003UCSDFeng 7 Black Holes BH production requires strong gravity, masses or energies above M D In 4D, M D ~ 10 18 GeV, BHs confined to astrophysics, form by accretion But in extra D with M D ~ 1 TeV, BHs may be produced in elementary particle collisions

8. January 2003UCSDFeng 8 A Schwarzschild BH (Q = J = 0) has radius In classical GR, expect a BH to form when two partons pass within r s of each other: Assume this, and that M BH = s 1/2. BHs from Particle Collisions Banks, Fischler (1999) Myers, Perry (1986) ^

9. January 2003UCSDFeng 9 Classic study for 4D, b = 0 collision: M BH ~ 0.8 s 1/2 D’Eath, Payne (1992) Heuristic argument for b > 0: J > 0  r s  r Kerr :  ~ 0.64  classical Anchordoqui, Feng, Goldberg, Shapere (2001) Classic study generalized to b > 0:  > 0.64  classical ; M BH > 0.71s 1/2 for b = 0, M BH > 0.45s 1/2 for b = b max Eardley, Giddings (2001) And to D > 4:  > 1.05  classical ; M BH > 0.6s 1/2 for b = 0, M BH > 0.1s 1/2 for b = b max Yoshino, Nambu (2002) Ida, Oda, Park (2002) BH Formation

10. January 2003UCSDFeng 10 For low mass black holes, brane, quantum gravity corrections are important. Require: Small statistical fluctuations in number of degrees of freedom Little back reaction from radiation Preskill, Schwarz, Shapere, Trivedi (1991) Both require large entropy S ~ r s 2+ n. BH lifetime  >> M BH -1 For n=6, S(5M D ) = 27, S(10M D ) = 59  (5M D ) = 10M BH -1,  (10M D ) = 12M BH –1 Giddings, Thomas (2001) Brane effects negligible Semi-classical analysis only valid for M BH > M BH min = few M D. Semi-classical Validity

11. January 2003UCSDFeng 11 Black Holes at Colliders What is the production rate? LHC: E COM = 14 TeV pp  BH + X Find as many as 1 BH produced per second Note, however, extreme sensitivity to M BH min. Dimopoulos, Landsberg (2001) Rizzo (2001)

12. January 2003UCSDFeng 12 Event Characteristics For microscopic BHs,  ~ 10 -27 s, decays are essentially instantaneous T H ~ 100 GeV, so multiplicity ~ 10 j : l :  :,G = 75 : 15 : 2 : 8 Emparan, Horowitz, Myers (2000) Signal: spherical events with hard leptons, photons De Roeck (2002)

13. January 2003UCSDFeng 13 Black Holes from Cosmic Rays Cosmic rays – the high energy frontier Observed events with 10 19 eV  E COM ~ 100 TeV But meager fluxes! Can we harness this energy? Kampert, Swordy (2001)

14. January 2003UCSDFeng 14 Cosmic Neutrinos Feng, Shapere (2001) Many possible UHE particles – use neutrinos:  N    dominates SM processes, since all partons contribute  pN    <<  pp. Protons are hopeless

15. January 2003UCSDFeng 15 The Signal Vertical atm. depth: 10 mwe Horizontal atm. depth: 360 mwe  BH: uniform at all depths pN  X: at top of atmosphere Signal: deep inclined showers; atmosphere filters out proton, nucleus background Feng, Shapere (2001)

16. January 2003UCSDFeng 16 Deep Inclined Showers Coutu, Bertou, Billior (1999)

17. January 2003UCSDFeng 17 Rates

18. January 2003UCSDFeng 18 Guaranteed:  photoproduction Choose most conservative: Protheroe, Johnson Fluxes Stecker (1979) Hill, Schramm (1985) Protheroe, Johnson (1996)

19. January 2003UCSDFeng 19 Additional sources may exist (for example, to solve the GZK problem) Below consider only  photoproduction; other sources may increase rates by 2 orders of magnitude Other Sources

20. January 2003UCSDFeng 20 Showers may be detected by ground arrays and air fluorescence Current: AGASA (ground), HiRes (air fluor.) Future: Auger (both) Apertures http://www.auger.org

21. January 2003UCSDFeng 21 Auger Observatory

22. January 2003UCSDFeng 22 Apertures Capelle, Cronin, Parente, Zas (1998) Diaz, Shellard, Amaral (2001) Anchordoqui, Feng, Goldberg, Shapere (2001) HiRes Collaboration (1994)

23. January 2003UCSDFeng 23 Lower bounds on M D from absence of BHs at AGASA and HiRes for M BH min = M D. For n > 3, M D > 1.5 – 2.0 TeV, most stringent bounds to date Current Bounds: AGASA, HiRes Anchordoqui, Feng, Goldberg, Shapere (2001)

24. January 2003UCSDFeng 24 For M BH min ~ 10 M D, well into classical regime, bounds are comparable to or exceed all other bounds M BH min Dependence Lower bounds on M D for n=1,...,7 from below x min = M BH min /M D

25. January 2003UCSDFeng 25 Future Prospects: Auger Auger begins 2004 — can detect ~100 black holes in 3 years Provides first chance to see black holes from extra dimensions m D (TeV) Number of BHs at Auger for n = 7, M BH min = M D

26. January 2003UCSDFeng 26 Comparison with LHC LHC predictions extremely sensitive to M BH min No Auger BHs, M BH min >5 M D  no LHC BHs Of course, we could see events!...

27. January 2003UCSDFeng 27 Black Hole Identification How will you know if you’ve created one?

28. January 2003UCSDFeng 28 S. Harris

29. January 2003UCSDFeng 29 BHs vs. SM BH rates may be 1000 times SM rate. But –large BH   large rate –large flux  large rate However, consider Earth- skimming neutrinos: –large flux  large rate –large BH   small rate Bertou et al. (2001) Feng, Fisher, Wilczek, Yu (2001)

30. January 2003UCSDFeng 30 Quasi-horizontal (dashed) and Earth- skimming showers (dotted) in 5 years. SM explanation (  BH =0) excluded at high CL.

31. January 2003UCSDFeng 31 What You Could Do With A Black Hole If You Made One Discover extra dimensions Test Hawking evaporation, BH properties Explore last stages of BH evaporation, quantum gravity, information loss problem ……

32. January 2003UCSDFeng 32 Additional Possibilities Under-ice: AMANDA/IceCube Radio: RICE, ANITA Space-based: EUSO/OWL These may provide BH branching ratios, angular distributions, etc. Anchordoqui, Goldberg (2001) Emparan, Masip, Rattazzi (2001) Uehara (2001) Ringwald, Tu (2001) Ahn, Cavaglia, Olinto (2002) Kowalski, Ringwald, Tu (2002) Jain, Kar, Panda, Ralston (2002) Alvarez-Muniz, Feng, Halzen, Han, Hooper (2002) Anchordoqui, Feng, Goldberg (2002) Iyer Dutta, Reno, Sarcevic (2002) Anchordoqui, Goldberg, Shapere (2002) McKay, etal. (2002)...

33. January 2003UCSDFeng 33 Conclusions Gravity is either intrinsically weak or is strong but diluted by extra dimensions If gravity is strong at ~ 1 TeV, we will find black holes in cosmic rays and colliders Anchordoqui, Feng, Goldberg, Shapere (2001) M D (TeV)